1. Field of the Invention
The present invention is concerned with a navigation unit for receiving navigation signals from a source thereof such as global positioning satellites. More particularly, the preferred navigation unit is configured to rack mount in order to connect with a remote, fixed antenna, and also configured for detached, battery-powered operation using a directly mounted helical antenna. The preferred antenna includes four antenna filaments composed of a thin film of conductive material printed on a flexible dielectric substrate rolled into a tubular shape in order to present the antenna elements in a helical configuration.
2. Description of the Prior Art
The prior art discloses navigation units operable for receiving navigation signals such as those from global positioning satellites. Known prior art units include those which can be permanently mounted to a vehicle for connection to a remote fixed antenna, and include hand-held units which can be transported by a user.
The hand-held units include an attached antenna which must be held erect during the time required to receive and process the navigation signals. Receipt and processing of the navigation signals can take a period of minutes and holding the erect for the required time can become tedious. Accordingly, the prior art points the need for an economically manufactured navigation unit which can be both rack mounted to a vehicle, and which can be conveniently detached for personal use away from the vehicle without the need for precise, steady, and vertical alignment of the antenna.